The rapid test for pregnancy can give both false positive and false-negative results. Everything depends on quality of the producer, intake by the woman of hormonal medicines and many other factors.
How does the test for pregnancy work?
Urine of the pregnant woman contains a horionichesky gonadotrophin – special hormone which is produced by structures of an embryo after it fastens to a uterine tube or a uterus. HGCh is produced in mother's blood, and then there is its conclusion through kidneys. The kind of the chromatographic analysis under the name an immunochromatography is the cornerstone of work of any rapid test. It is based on interaction of the defined substance with antibodies to it. In urine of the pregnant woman for 7-10 day after fertilization the HGCh level is 25 mME/ml. It is the minimum concentration which is detected by immunochromatographic tests at once.
Tablet systems for definition of pregnancy are more advanced tests. Due to simplicity of carrying out in them emergence of mistakes is minimized – the drop of urine is applied directly on the test.
Misuse of the test
The young ladies who are afraid of unwanted pregnancy and also the woman, the long time dreaming of the child often think of whether the test can be mistaken. It in many respects depends on observance of rules of its carrying out. For example, if "to overdo" the test more than 5 minutes as it is specified on packing, the weak false positive strip can appear. It arises because of destruction of conjugates and release of dye owing to evaporation of water from the surface of rapid test. That "precisely to make sure", it is not necessary to wait for 10 minutes instead of 5. Nothing good from this will turn out. It is better to study attentively the instruction with evident photos.
Low-quality producer and administration of drugs
In not really qualitative tests indistinct spots most of which often women like to take for a false positive second strip can be formed. It occurs because a complex antitelo-HGCh-krasitel reaches reactionary zones later, than from a conjugate dye is chipped off. At the woman taking the drugs with the maintenance of HGCh, for example, "Profazi" and Pregnila stimulating an ovulation upon termination of a course of treatment the level of hormone can remain up to two weeks. It is better to hold off the test for this period, otherwise it will show the wrong results.
Electronic tests in which need to estimate result disappears as on the screen the inscription "yes" or "no" appears became widespread.
False-negative result
False-negative indications of tests – the phenomenon rather widespread, unlike false positive. Most often they turn out when the term of pregnancy is still very small, and HGCh contains in smaller quantity, than it is necessary for reaction of the text. Happens and so that the test in itself is insufficiently sensitive. Then on early terms it will not be guaranteed to show pregnancy.